In providing desiccant inserts for air drying equipment, as explained in a companion case entitled "Telescoping Canister For Filter Materials" filed on even date herewith by the same inventors, the desiccant insert includes a flexible manipulative bag for containing the desiccant. The bag per se has certain disadvantages as discussed in the companion application. The flexible bag is employed in a cavity of an air drying container connected in a conduit or pipe of an air brake system, for example, to remove moisture from the brake system.